Weekly Subject 02 - Safety and Computers

Safety and computers is the next logical choice for us to discuss. Why? For one reason if your on these VirDr forums you will one day want to do some "hardware stuff" to your computer. Now in case you haven't noticed you have a delicate body which can't stand pain. Voltage and amperage can cause both pain and death. Consider this, a very small voltage with some amperage can take you out of lifes picture.

This does not mean that that you cannot work around your computer. Quite the contrary, by following some simple rules an enjoyable experience will ensue in safety.

We will explore this subject in detail and remember any question you have in your mind, please please, ask. As has been said many times we do not consider any question as dumb or stupid. And this applies especially to our newer members just getting in contact with the world of computers. The whole reason for this thread and the rest of VirDr is for you who are inquisitve and wish to learn more than you know now.

We just finished surge protection which protects your computer. Now for Safety and Computers which will help protect you.

The first question is: How do I know if I'm being safe around my computer? https://discussions.virtualdr.com/

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Computers are required to meet certain codes so that a person can use them with a certain level of safety. This is regard to electrical [paramount], and other requirements.
EDIT: This is in regards to their personnal safety and to the safety of the equipment.
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[This message has been edited by Train (edited 06-01-2001).]

Can you expand on that a little? https://discussions.virtualdr.com/

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This by nature has to be a little technical.
The equipment is designed and tested to meet IEC 950, the standard for the Safety of Information Technology Equipment. This is the International Electrotechnical Commission's safty standard.

The standards provide general saftey design requirements that reduce the risk of personal injury to both the computer user and service provider. These standards protect against the following hazards:

• 1. Electrical shock
  Hazardous voltage levels contained in parts of the product.
  2.Fire
  Overloads, temperature, mateeerial flammability.
  3. Mechanical
  Sharp edges, moving parts, instability.
  4.Energy
  Circuits with high energy levels [240 volt amperes] or potential as burn hazards.
  5. Heat
  Accessible parts of the product at high temperatures.
  6. Chemical
  Chemical fumes and vapors.
  7Radiation
  Noise, ionizing, lazer,ultrasonic wav.

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So this is why I can buy and start using a computer without any concern except for what is mentioned the setup manuals that comes with the computer. A code governs the manufacturers.

Whenever accessories are plugged in or disconnected, should the computer be off and unplugged?

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All but USB and Firewire must be done in the shutdown with the main power switch turned off or unplugged. The reason is most systems have a instant on type circuitry and there is power to the motherboard. Things could be damaged.

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In other woids, if you're going to work inside the case, just because it's "off" doesn't mean there's no power in there. UNPLUG. Use an anti-static wrist strap or touch the metal chassis first before poking your digits in there. Power supply or monitor: you have some cute little surprise packages in those called capacitors. Even if unplugged for quite a while, they can zap you real good; in the monitor, they can even kill if the conditions are right.

Should I clean my monitor when it is on? I have read where it is dangerous to do this.

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What happens when you get hit with a jolt from a capacitor? What could kill you?

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Capacitors are somewhat like batteries in that they store electricity, but at much higher amperages. Amps are what kills.



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Extremely fast synapses occur from the point of contact to the brain, where your pain center passes on an urgent message to your logic centers: "What in THE H&^% were you thinking about?????". The message is then passed onto the heart: Palpatate! Palpatate! DIVE! DIVE! DIVE!". If the shock is just the right amperage, the message is: "Forget the palpatation! Just quit!".

Is there a difference between coming in contact with AC or DC. Is one more lethal than the other? https://discussions.virtualdr.com/

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I would guess AC is more lethal. AC current affects the heart, DC doesn't.

Both are lethal at about the same extent. Hard to believe, but it is true. Remember static electricity and lightning are considered to be DC.

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Now we know that a computer under normal cicumstances will not hurt us from electrical shock.

But I want to upgrade, say, my ram from 64 to 128. What are the safety precautions to take in completing this procedure from start to finish?

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Hmmmmmm....so to get hit with 5,000 volts DC or AC (with the amperage say...oh...around 5)? Decisions, decisions.... https://discussions.virtualdr.com/

Think I'll sleep on it...Nite!

EDIT: Some of the following post are not to scare people but are Technical in nature to try and figure if the equipment in various countries are the same with different names is all. And it turns out to be true. All toward our safty.


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[This message has been edited by Train (edited 06-03-2001).]

In my 35 years as an electronic tech., I've had the opportunity to be knocked on my rear by all sorts of excited electrons; AC, DC, RF, microwave, high Amp and low. I've also had the 3/4 million volts from a DeGraff generator pass through me and light a florescent bulb without harm (lots of volts, no amps).

When you hook yourself up to an antistatic strap or grab the chassis, you create an excellent path for electricity, right throutgh your body. While this protects the delecate electronic parts from being harmed by a atatic discharge, it places you directly in harms way. What we techs are taught to avoid is giving the electricity a path through either your heart or your brain bucket.

Electricity follows the shortest path so if the grounding strap is attached to the arm you are doing the fingerpokin' with the brunt of the shock is restricted to your arm. If you ground one hand and poke around with the other the path goes right across your chest and you put your ticker right in the line of fire.

I have NEVER used a grounding strap, and I handle delecate computer components all the time. I use one simple rule. TOUCH THE CHASSIS FIRST AND LAST. It's safe for me and the components.

DA

I always wear a wrist strap connected to earth via a mains socket (turned off of course), this is something I hate doing. If I was to not bother in future and I was to keep my arm touching the case will the power supply have to be plugged in so it is connected to Earth, or is it simply enough for me and my machines case just to be in contact?

It is best to have an earth ground, but the important thing is to have the components and you at the SAME potential so you don't jump a spark when you touch the component. Momentarily touching the chassis usually accomplishes this quite well.

If you find that you get frequent shocks from doorknobs and such around your house or office, spray the carpet with static guard and insulate yourself from the carpet with a rubber mat or rubber-soled shoes in the work area.

DA

dacomputers, as I usually work in a carpetted room, its probably best that I continue with my strap, thanks

'morning beauties (once you get up),

I've worked the insidings of computers at home for over 15 years now. In fact, that is what got me hooked on engineering - that and NC/CNC machines...
I've never owned a wrist strap, but I've always made a point of discharging myself by touching the chassis first, before I touch anything inside the machine. Never had anything destroyed by static discharge.

I've had one experience,though, where I thought I had destroyed an IBM TP760 completely - but no harm came to the TP, luckily.
I had switched off the machine (placed in a dock) and was about to draw a phono cable from the speaker-outlets in the room (radio switched off to stand by) to the audio line-in on the computer, to record some of my old vinyl records on CDs.
Thinking this was an external connector (as it is..) I didn't pull the plug. I soon realized my mistake: Before I could stick the phono plug into the line-in socket, a small spark jumped between the two and all lights and everything else went dark - the house was without any power at all.
I went to look at the fuseboard and found that the HFI-relay (don't know the english name - may be the same? Works fx. against what we call "creeping currents") had kicked in and cut all power to the house. Once I'd pulled the plug I could reset the HFI-relay and power came back on.

Thinking a bit about it I asked myself how the current had gotten there? I then realized what my mistake was: The speaker-outlets in the room are connected to a "link" (Beo-link - B & O HiFi...if anyone knows them) that transmits commands from a remote contr. to the system placed in another room in the house - gives you music in every room of the house via these links once you install speakers.
Although the radio system had been put into stand-by, this link was still very much alive and powered (by the radio). Cutting off the speakers (at a switchbox) cut the power and work could be resumed - to my relief noothing had happened to the PC.

Never underestimate electricity - neither the strong nor the weak currents. They can be equaly destructive to sensitive equipment.

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Karl, Denmark
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"..and may The Force be with you too..."

[This message has been edited by kallikru (edited 06-02-2001).]

[This message has been edited by kallikru (edited 06-02-2001).]

Good Morning All, Looks like a 24/7 operation around here but besides not like being shocked this ole body still needs sleep. https://discussions.virtualdr.com/

Thanks to all of you for your inputs.

Let's see two questions were asked and not answered, so to rephrase:

How do I clean my monitor glass safely?

I want to change a stick of RAM so memory will operate faster. This means going into the computer - opening up the case. How is this accomplished safely both for myself and the computer?

And while you experts think about how to answer these two questions there are a couple of Honey Dos to be accomplished. https://discussions.virtualdr.com/



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1) I clean my monitor on or off all the time. Doesn't seem to make a difference.
2) Just replaced the RAM in my machine last night.
Power off.
Unplug everything
Open the case and touch bare metal part of case while standing on anti static mat wearing rubber sole shoes.
Don't use power tool such as screwdrivers, power saws, grinders, etc. inside the case.
Carefully replace the sticks while not touching other things when possible.
Replace the cover.
Plug everything back in.
Hit the power button.
Hold your breath.

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Si Hoc Legere Scis Nimium Eruditionis Habes.
(translation: If you can read this you're
overeducated)

[This message has been edited by Trish-A (edited 06-02-2001).]

One suggestion on cleaning your monitor. If you use something water based such as "windex"? Use paper towels rather than cloth.Cloth may be/contain nylon,dacron or other synthetics conducive to static. Also, spray the cleaner on the towel,"not" directly on the screen. If your not quick enough, it could leak inside at screen bottom. Use alcohol to clean the cabinet using same application method as above.

Most carpeting nowadays is synthetic and can generate a healthy static charge. That's why, not having a work room available in my Apt. i always work on my equipment in the kitchen.(staying away from water sources of course) https://discussions.virtualdr.com/ Linoleum type floor coverings are also synthetics, but don't give you the "combing the hair" type of static buildup that carpeting can..

Also, i ALWAYS power completely down and unplug before "going in" to the box. Good idea to leave it sit for an hour or so before opening things up. Gives those nasty capacitors time to discharge.

Good rule of thumb for "anyone",,,Think, before you touch!! (ain't it fun tho'? https://discussions.virtualdr.com/ )

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When your through learning,,,your through.

I'm an electrician, and here in the UK we have what is probably the highest electrical safety standards in the world, so I guess that qualifies me to say a few words about electrical safety. One of the very first things drummed into us at college is: "THERE IS NO SUCH THING AS A SAFE VOLTAGE". Having said that, when we design electrical systems over here we have to make sure that under no fault conditions can the voltage on exposed metalwork rise above 50v (except on construction sites and agricultural installations when it has to be >25v). You can read into that what you will.
As said above, it's the current that kills, keep it below 50mA and you'll be as safe as houses, you can ensure you keep below this level by inserting a 1 megohm resistor in your wriststrap, that way you get the best of both worlds, you protect the chips and yourself.
There is no difference between AC & DC as far as safety is concerned.
Be very careful inside monitors, there are very voltages inside. I happily mess about with 415v 3-phase systems all the time, but I don't like going inside a monitor or TV!
One of the best investments you'll ever make, is to have a Residual Current Device (RCD) installed in your homes (they may be called something else outside the UK). Correctly installed and rated they'll trip long before you get anywhere near a lethal current, and if you've got pets that like to chew through power cords then they are a must.

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Nick.

Just got back. Hey, you all posted good how to "stuff" from your personal experience. This is great. I can picture in my mind what you are saying. You do not find this information in any text books that I know of. This is the type on information that will help the new comers and save them alot of time wondering about.

Now, should we expand on replacing a stick of RAM? The actual how to. As a person opens up a case can you cut yourself on anything for example? Anything else that you would need to watch out for?

Trish-A gave a very good comprehensive list. Should this have more detail since we're targeting people just starting out?

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Hey SSparks,
I think your RCD device sounds like the HFI-relay I mentioned. HFI is mandatory here in DK. It's located at the fuseboard and requires a routinely one-time-a-year activation to ensure it's working properly. It will some times cut the power even before the fuses blow - sounds familiar?

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Karl, Denmark
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"..and may The Force be with you too..."

1. I believe the "RCD" and "HFI" are the same and around here I think they are called "EFI" for electrical fault interrup(sp?).
2. As far as cleaning moniters, it depends on what kind of moniters. Glass faced, TFT or LCD are different. At work we never use windex as it builds up static charge and attracts more dust. TFT's have special cleaning pads to ensure you do not scratch the surface.
3. I never clean any of them with power on. Been zapped to many times on glass faced moniters and old TV's. Also easier to see finger prints.
4. In school there were jokes about AC/DC shocks and being able to tell them apart by rather your arm flapped in sync with AC or was sraight from DC. Don't know about the AC part, but while test benching a counter radar box the intermediate power supply put 1500 vdc across my finger tip and the probe. My arm really was straight till I bounced off the roll around tool box behind me. Then all I could smell was burnt flesh. My finger looked like I had laid a hot soldering iron on it. https://discussions.virtualdr.com/

https://discussions.virtualdr.com/ Opovet https://discussions.virtualdr.com/

ps: now I try to limit my work to 12 vdc or less. https://discussions.virtualdr.com/


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I know it is true because I read it on the internet from a VirtualDr link!!

GFI/GFCI I do believe this is what you folks are refering to. If not link in a photo if possible.

Now the code I referenced earlier covers the outside of the case and to a extent the inside as well.
But, Some things you can find inside.
Sharp edges that cut.
Voltages that can hurt or harm you.
Just to name a couple.
And if you use the wrist strap, make sure the resistor is in there and wear it on the arm that you are using and "Keep the other one in your pocket" as I was instructed.

Before replacing RAM it pays to take a look inside your computer so that you know what you are getting into.
This is in reference to the fact that I have found the ram slots behind the powersupply and some research told me that the motherboard was mounted to a removable board and where the screws where that held it in place. So, I wound up almost totally dismantalling the case to put the ram in. It was a straight forward job to put the ram in. Just lined up the slots in the ram to the slots in the motherboard and using even pressure on both ends of the ram pushed it in and the keepers on both ends rolled up and locked into place.
Then on others it has taken longer to shutdown the computer and unhook everything than it did to open the case and insert the ram.

Yes, some countries have better electrical codes than we do in the US. But we use a 120V base instead of 240V in our homes. At work, now that is different .
Will see if I can find a GFI graphic.


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Computer crashed on a stack overflow error, posted on Win 98 board, found out what I was doing wrong and went into running some checks. Sorta lost track of time.

Can anyone think of anything else as far as personal or computer safety goes that should be added?

Throughout out Weekly Subject topics safety will come up in a practical sense.

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To add to the list on replacing RAM or anything else inside the case snarfll's tip on letting it set for a bit is a very good idea.
Have plenty of good lighting so you're not trying to work in shadows.
Have the machine setting on a stable platform (I place a rubber mat under mine so it doesn't slide).
You may be replacing RAM to make your PC run faster, but here you want to slow down and think about what you're doing. Replacing RAM is a fairly simple task, but if you rush the job you can screw things up fast. Pushing too hard to seat the chips can damage the mainboard.
Rummaging around blindly can unplug cables or dislodge jumpers.
Both opening and closing the case can result in cuts or pinched fingers.
I've seen people with there hands inside a machine, pushing on something hard enough to rock the work table while they're looking and talking to me and I'm thinking, "I'm glad that thing doesn't belong to me".

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Si Hoc Legere Scis Nimium Eruditionis Habes.
(translation: If you can read this you're
overeducated)

GFI Breakers

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How about one more example having to replace something. Maybe one of the cards. Same rules apply?

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Quote:

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Originally posted by Train:
GFI/GFCI I do believe this is what you folks are refering to. If not link in a photo if possible.

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Well, I found a picture - and a description in Danish (also a language.. https://discussions.virtualdr.com/) - for those not fluent in this language: http://sikkerhed.biologi.sdu.dk/el_sikkerhed/hfi.htm .

Translation: "An HFI breaker/relay is normally placed before the fuses. It's purpose is to cut the power if more than 30mA of the current being sent finds other ways to the ground (fx. to the ground through a person)...." - sounds like the GFI/GFCI.
Somewhere else I read that "(HFI)..can be very sensitive to lightning.." - maybe that's why UPSs aren't very much used here...? I've been thinking for some time to get one, though.


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Karl, Denmark
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"..and may The Force be with you too..."


[This message has been edited by kallikru (edited 06-03-2001).]

kallikru
I agree it is the same, just put in a different location in the circuit. As for using it for a lightning arrestor [protection from lightning] all test I have knowledge/read about, they failed.

Remember 1000V at 30ma going through a ps will have a yield of 240V at 125ma or 120V at 250ma. But of course lightning is much higher in voltage than 1000V.

Also when you reach for someone and the spark that jolts the both of you, it is a minimum of 50,000 volts. That is what it takes for the spark to jump from one person to another. Now if that static electrical charge were to hit the components in a computer. You can probably kiss something in there goodby.

Nice translation.

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The picture of GCI breakers that train posted are what we call MCB's (Miniature Circuit Breakers), they are purely an overcurrent device, and have no protection against electric shock. There is a device available as a direct replacement for them called RCBO's over here (Residual Current Breaker / Overcurrent device), which combine both devices into one unit.
The HFI device described by kallikru sounds exactly like our RCD's. They always have a test button on them, and are usually rated at 30mA, though they are available in other ratings. In the UK, if fitted, the test button must be operated every 3 months, and the RCD must be tested using an RCD tester whenever the periodic inspection is performed.
Out of professional curiousity I'd like to know what the three-letter-acronyms stand for (GCI, HFI, etc.)

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Nick.

[This message has been edited by SuperSparks (edited 06-03-2001).]

From my link above.

A Ground Fault Circuit Interrupter, commonly called a GFI or GFCI, is installed on exterior outlets, or in areas where there is a water source (bathroom or kitchen sink) near the outlet. GFI units are designed to protect the users of electrical appliances from electrocution because of hazardous ground faults or short circuits, by automatically turning off electricity when a fault is detected

Now this business is getting interesting to me.

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You've got it Train - that's a perfect description of an RCD. I wish someone would standardise these names, at least for the English speaking world. That picture you provided the link for looks like our standard circuit breakers, though. Our RCD's are normally twice the width, and always have a button marked "Test" on them, plus a clearly marked mA rating on the front.
And now that I know what GFI stands for, it makes sense. A few years ago we used to call ours ELCB's (Earth Leakage Circuit Breakers), which is much the same description. Then, of course, it was decided to change the name to the cryptic Residual Current Device, which only makes sense to anyone who has a detailed knowledge of how they work (which, I might add is very interesting).

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Nick.

[This message has been edited by SuperSparks (edited 06-03-2001).]

There a large number of various type components that fall into this catagory.
Some are outlets with the test switch, breakers, mounted into extention cord, but all have the same purpose it seems. But, have to admit I like the 10ma to the 30ma idea best. Theytend to promote safety.
But, good saftey habits beat equipment any day.

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